Ice dam risk in Channahon, IL
How often ice dams form in Channahon
11.3 dam days a winter
Moderate risk. On an ordinary house in Channahon, conditions for an ice dam come on about 11.3 days in a normal winter, mostly in January and February.
Channahon averages 18 inches of snow a year and about 37 days with snow on the ground. Most of it comes and goes within a few days. The conditions that make a dam need all three at once: snow, cold at the eave and heat above it.
What your attic does to that number in Channahon
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 5.9 | Moderate |
| Typical, some insulation, not air-sealed | 11.3 | Moderate |
| Older or poorly insulated, warm attic | 18.2 | High |
Sealing and insulating a typical attic takes out about 5.5 days a winter here. It does not move the risk band, but it shortens every dam. An older house with a warm attic should expect closer to 18.2 days.
Preventing ice dams on a Channahon roof
- Air-seal the attic floor: the gaps around the hatch, light fixtures, plumbing stacks and the top plates of interior walls. This is the fix that removes the cause, and it usually costs less than a season of contractor ice removal.
Which to spend on first: air sealing or heat cable.
Channahon winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 6.4 | 14.4 | 5.2 |
| February | 5.2 | 10.7 | 3.3 |
| March | 0.4 | 3.2 | 0.6 |
| November | 0.3 | 1.1 | 0.1 |
| December | 6.1 | 7.1 | 2.1 |
Channahon next to nearby towns
Channahon ranks 170 of 225 Illinois cities here for ice-dam days, behind Arlington Heights at 21.5 days.
- Minooka, IL 2 mi, 8.8 days
- Shorewood, IL 7 mi, 8.8 days
- Joliet, IL 9 mi, 8.8 days
- Morris, IL 9 mi, 11.4 days
- Crest Hill, IL 13 mi, 12.2 days
Where these numbers come from
NOAA 1991–2020 climate normals from Channahon Dresden Isl Dam, 2.0 miles from Channahon. A dam day is a day with snow on the roof and freezing at the eave while heat or sun melts the snow above it. This describes a normal winter, not this one.
- Snow-on-the-ground counts come from a second, nearby station, because the closest one does not record them.